A fuel cell system produces an electric voltage and makes this available to electric users. The fuel cell system has a fuel cell unit, which usually comprises a plurality of fuel cells, for this purpose. The individual fuel cells have an anode and a cathode, whereby the cathode dissociates and ionizes oxygen and the ionized oxygen migrates through an electrolyte of the fuel cell to the anode and reacts with hydrogen ionized by the anode into water. Thus, an electric potential or electric voltage, which is made available to the electric user, forms at the electrodes of the fuel cell according to the Nernst equation. The chemical reactions essential for the functionality of the fuel cells and especially the conductivity of the electrolyte for ionized oxygen start from a certain temperature, which is usually a few 100° C. On the other hand, the anodes are supplied with an anode gas usually via a reformer of an anode gas feed means, which supplies the anodes with a reformate gas as the anode gas. The reformate gas essentially comprises hydrocarbons, whereby the reformate gas usually has a temperature of a few 100° C. If the anode has a temperature which lies below a critical temperature, i.e., especially in case of a cold start, i.e., in a state, in which the anode has an ambient temperature or room temperature, then this leads to a deposit of hydrocarbons of the reformate gas on the anode surface. This is especially the case if the fuel cell, and especially if the anode, is brought to operating temperature with the reformate gas. The deposit of hydrocarbons on the anode surface leads, however, to a reduction in the chemical reactivity of the anode, which may lead to a failure of the anode and thus of the fuel cell system.